Human glomerular endothelial cells are isolated and cloned from glomeruli obtained from nephrectomy specimens which have been removed for medical or surgical reasons. Some glomeruli will be obtained from specimens which were initially designated to be used as cadavor transplants but were not able to be utilized for technical or other reasons. The principal assays to be used will be to assess the procoagulant activity of supernatants and cytoplasmic preparations from the cells.